The invention relates to a bipolar forceps, more particularly for RF coagulation, as per the preamble of patent claim 1.
In surgery, bipolar forceps are used for coagulating the tissue of a patient. To this end, radiofrequency AC current is generally conducted through the tissue in order to heat and coagulate the latter. The forceps used for this purpose have differently shaped limbs, depending on intended use, with respectively one electrode being formed at the distal tips of the two limbs. The tissue to be coagulated is brought between the electrodes. The RF current is supplied via a plug-in connector attached proximally on the forceps and conducted through tissue via the electrodes.
A problem in the case of these bipolar forceps is that the RF current heats not only the tissue situated between the electrodes. The electrical contact resistance between the tissue and the contact areas of the electrodes touching the tissue also leads to heating of the electrodes. The heating of the electrodes can lead to the tissue sticking to the contact area of the electrodes. This leads to dirtying of the contact areas by the stuck-on tissue and increases the contact resistance for subsequent coagulations. Moreover, the tissue sticking-on can lead to stuck-on tissue parts being carried along when the forceps is removed and the tissue being damaged as a result of this.
In order to counteract this sticking-on of the tissue, the heating of the electrodes is known to be reduced by providing the electrodes with a metal, which has a high thermal conductivity for dissipating heat from the contact area of the electrodes. Moreover, this metal must have good electrical conductivity in order to conduct the RF current. Finally, the metal must be biocompatible, i.e. it must not damage the tissue chemically. Suitable metals with these properties are, in particular, the precious metals silver and gold, wherein silver should be preferred, more particularly also for reasons of cost. In the case of a bipolar forceps known from EP 1 210 022 B1, the distal tips of the limbs, consisting of stainless steel, of the forceps are for this purpose surrounded by a layer of silver or gold. This layer forms the electrodes with the contact areas thereof and at the same time forms a heat reservoir with a relatively large heat capacity for absorbing heat dissipated from the contact area. In the case of a bipolar forceps known from DE 10 2008 022 889 A1, a channel leading to the contact area of the electrodes is worked into the distal ends of the limbs, consisting of stainless steel, of the forceps, which channel is filled with silver to form a heat conduction channel for dissipating the heat from the contact areas. In these known bipolar forceps, the formation of the heat dissipation is connected with additional work steps during the production of the forceps.